This invention relates to lids for mounting on the top of aerosol cans or the like, and particularly to a lid including mounting flanges configured to engage an outer annular lip provided near the top of the aerosol can. More particularly, this invention relates to a sturdy lid that is mounted on an aerosol can to support a heavy weight loaded on top of the lid without deforming the lid so that it bears down against the aerosol spray button and causes premature release of the pressurized contents of the aerosol can inside the lid.
Everyone has seen an aerosol can provided with a plastic lid mounted on top of the can to cover the aerosol spray button. To release the pressurized contents of the can it is customary to remove the lid, hold the can upright, aim the discharge opening in the right direction, and depress the aerosol spray button. Such lids are typically formed in a mold using a plastics material such as polypropylene or high density polyethylene. The lids are usually molded to include a shell and various internal ribs and flanges. Of course, these molded lids can also be used to cover the discharge openings provided in containers other than aerosol cans.
Lidded aerosol cans are typically stacked on top of one another in packing boxes so that large numbers of filled cans can be shipped or warehoused. These boxes often contain many layers of stacked lidded cans and, as a result, the lids on the lower layers of aerosol cans are carrying the heavy weight of all of the cans stacked above in the upper layers. These filled packing boxes are often handled roughly during shipping and warehousing, and this type of handling can also increase the magnitude of the loads applied to the lids on the aerosol cans in the packing boxes. Of course, lidded aerosol cans may also be stacked on top of one another on a shelf to provide an attractive display in a retail store.
One problem with many conventional aerosol can lids is that they do not have a lot of "stacking strength" and thus are not always able to support the heavy weight of a stack of aerosol cans or strong, dynamic impacts of the type frequently encountered during shipping and warehousing. Unless an aerosol can lid has a sufficient stacking strength, it may deform, shift, or collapse somewhat under a heavy static or dynamic load, leading to unexpected discharge of the pressurized aerosol can contents while the lid is still in place on the top of the can.
Some conventional aerosol can lids are molded to include eight to ten vertical stacking ribs arranged around the perimeter of the inner side wall of the lid and spaced apart from one another at even increments. It has been observed that these vertical ribs are sometimes subjected to severe shearing loads created by an overlying heavy stack of aerosol cans or other heavy static or dynamic loads. These severe shearing loads sometimes result in one or more sheared or permanently deformed vertical stacking ribs inside the lid. This unpredictable occurrence sometimes goes undetected until the damage to the lid has already occurred. This damage is characterized by reduction in stacking strength of the lid and creation of an inconsistent or non-uniform stacking area on the ribs. Further, these conventional circumferentially spaced-apart vertical stacking ribs are subject to "plastic rollover" which again results in reduced stacking strength, etc. For example, plastic rollover is characterized by rolling and deforming rather than shearing and can occur wherever there are sharp edges, undercuts, or insufficient draft in the mold. Another problem with some conventional molded aerosol can lids is that it is sometimes difficult to strip these lids out of the mold without causing some deformation to the internal stacking ribs and thereby causing the lid to have reduced stacking strength.
What is needed is a sturdy aerosol can lid that is configured to mount on an aerosol can in such a way as to provide as much stacking strength as possible to prevent damage to the lid in unusual shipping, displaying, or warehousing conditions and thereby prevent premature release of the contents of the aerosol can while the lid is in place on the can. An improved lid having mounting flange means appended to the lid and configured to engage the aerosol can and support heavy compression loads placed on the lid without easily shearing, shifting, or deforming would avoid the shortcomings of conventional aerosol can lids. Ideally, such a mounting flange means would be configured to make it easy to strip the improved lid out of its mold without breaking or shearing the mounting flange means.
According to the present invention, an improved lid is provided for mounting on an annular lip around the top of a can. The lid includes a shell, a lid-retaining portion, and a hook-shaped load-distributing member. The shell has an inner wall and the lid-retaining portion is appended to the inner wall of the shell and positioned to engage the annular lip to hold the lid in place on the can.
The hook-shaped load-distributing member is also appended to the inner wall of the shell and is positioned to hook onto and engage the annular lip lying around the top of the can. The hook-shaped load-distributing member functions to distribute an external compression load applied to the lid from the lid to the can to maximize the compression loading capability of the lid and enhance the stacking strength of the lid.
In preferred embodiments, the hook-shaped load-distributing member has a conical shape positioned inside the shell to lie above the lid-retaining portion. Once the lid is mounted on the can, the annular lip is trapped between the overlying conical hook-shaped load-distributing member and the underlying lid-retaining portion. The annular lip of the can includes a circular bottom edge engaging the lid-retaining portion and a circular top edge engaging the conical hook-shaped load-distributing member.
The conical hook-shaped load-distributing member includes an annular slanted portion that converges toward the central vertical axis of the can and engages the circular top edge of the annular lip. Essentially, the annular slanted portion cooperates with the cylindrical inner wall of the shell to define a circular channel therebetween. When the lid is mounted on the can, the annular lip on the top of the can fits into this circular channel. If a heavy load is placed on top of the lid, the lid is urged downwardly toward the can and the annular slanted portion of the conical hook-shaped load-distributing member transfers that load from the lid to the can. This feature advantageously enhances the stacking strength of the lid as well as to promote part removal during ejection of the part from the mold.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best ode of carrying out the invention as presently perceived.